"Supersize" portions of chips and fizzy drinks at the world's largest fast food retailer are being taken off the menu.
A Big Mac contains 493 calories
McDonald's has announced it will put a stop to supersizing by December.
It plans to introduce more lower-calorie and lower-fat options alongside the milk, yoghurt and fruit offered.
The company has faced legal action over obesity in the US, where one group of children claimed its food was responsible for health problems.
In the UK, McDonald's says it is mindful about the obesity debate but that supersizing alone - where drinks and fries are upgraded from a large portion to an even bigger one - does not cause obesity.
The menu change came as Health Secretary John Reid called for a public debate on how best to improve the nation's health.
He launched a three-month consultation to find ways to tackle "worrying trends", including obesity.
It will pose questions on issues such as whether confectionary should be displayed on supermarket check-outs and food advertising on TV.
But Culture Secretary Tessa Jowell has poured cold water on a junk food ad ban, saying she is sceptical about the merits.
McDonald's says it is phasing out supersizing as it only represents a tiny portion of its business - 0.1% of total sales - and because its menu is being reviewed to meet customer expectations.
To compare, in a portion of large fries, customers can expect 412 calories and 18g of fat, according to nutrition information on the company's website.
That increases to 486 calories and 21.2g of fat in a supersize portion,
'Super Size Me'
While a large Coca-Cola at McDonald's provides 226 calories, a supersize Coke comes in at 323 calories - 97 calories more.
A supersize Coke and fries with a Big Mac contains 1,302 calories and 44.1g of fat in all.
Supersizing has received negative publicity following Super Size Me, a film by American Morgan Spurlock.
He set out to discover the effect of living on nothing but McDonald's for a month, upgrading to supersize portions when offered.
The film follows his 25lb weight gain and the health effects on his body, including his liver and cholesterol levels.